Activation of Renin-Angiotensin System in Maintenance of High Blood Pressure in Uncomplicated Pheochromocytoma--A Case Report

In a patient with an uncomplicated pheochromocytoma, we observed high basal value of plasma renin activity (PRA), 16.2 ng/ml/h, and a remarkable elevation in PRA from 18.2 to 90.4 ng/ml/h and concomitant blood pressure reduction following a single oral administration of 25 mg of captopril. The response was same as that observed in renovascular hypertensives, and disappeared during the period of α-, β-blocker administration or after the surgery. Basal PRAalso returned to low normal level. The reninangiotensin (R-A) system probably had a role in the maintenance of high blood pressure. The mechanism of the activation of the R-Asystem was thought to be renal vasoconstriction due to excessive circulating catech olamines.